White gold was invented in the 19th century where it was alloyed with palladium. It became commercially available as of 1912 in Pforzheim, Germany and gained popularity in the mid-1920's as a low cost substitute for platinum. It is an alloy of gold with copper, zinc and nickel. In more recent times the nickel in this alloy has often been replaced by a platinum family metal due to allergic reactions. The different recipes produce different alloys which, naturally, have different characteristics in terms of ductility, malleability and hardness. These differing properties make different alloys suitable for different purposes.